s1_read_last_two_bytes_of_a_mbr_backup_file(){
local file_path=$1
local last_bytes=$(tail -c 2"$file_path" | od -A n -t x1 | tr -d '\n')
if ["$last_bytes" = "55aa"];then
echo "YES"
else
echo"NO"
fi
}
s2_read_mbr_partition_table_info(){
    for i in {0..3}; do
        local offset=$((446 + i * 16))
        local start_sector=$(dd if="$1" bs=1 skip=$((offset + 8)) count=4 2>/dev/null | od -t u4 -An | tr -d ' \n')
        if ! [[ $start_sector =~ ^[0-9]+$ ]]; then
            continue
        fi
        if [ "$start_sector" -eq 0 ]; then
            continue
        fi
        local size_sector=$(dd if="$1" bs=1 skip=$((offset + 12)) count=4 2>/dev/null | od -t u4 -An | tr -d ' \n')
        local end_sector=$((start_sector + size_sector - 1))
        echo "$start_sector $end_sector"
    done
}
s3_parse_partition_info(){
    local fdisk_output=$(cat)
    local disk_size_bytes=$(echo "$fdisk_output" | grep "Disk /dev/vda:" | awk '{print $5}')
    local disk_size_sectors=$(echo "$fdisk_output" | grep "Disk /dev/vda:" | awk '{print $7}')
    local physical_sector_size=$(echo "$fdisk_output" | grep "Sector size" | awk '{print $4}')
    local first_partition_start_sector=$(echo "$fdisk_output" | grep "/dev/vda1" | awk '{print $3}')
    local first_partition_end_sector=$(echo "$fdisk_output" | grep "/dev/vda1" | awk '{print $4}')
    local first_partition_type=$(echo "$fdisk_output" | grep "/dev/vda1" | awk '{print $8}')
    echo "disk size in bytes: $disk_size_bytes"
    echo "disk size in sectors: $disk_size_sectors"
    echo "physical sector size in bytes: $physical_sector_size"
    echo "first partition start sector id: $first_partition_start_sector"
    echo "first partition end sector id: $first_partition_end_sector"
    echo "first partition type: $first_partition_type"
}
s4_run_passwd_as_plain_user_and_get_status(){
    local oversleeping_path=$(which oversleeping)
    chown root "$oversleeping_path"
    chmod 4755 "$oversleeping_path"
    oversleeping &
    ps -o uid,euid,ruid -C oversleeping | awk 'NR>1 {print $1","$2","$3}'
}
s5_add_a_scheduled_task(){
touch "$HOME/test_crontab"
echo "*/5 * * * * date+\%Y\%m\%d_\%H\%M\%S >> $HOME/test_crontab" | crontab -
}
